Plain of Jars, region, N Laos, at the northern end of the Annamese Cordillera. Over 300 jars, c.1,500 to 2,000 years old, are scattered across its landscape. Averaging 272 lbs (600 kg), the jars range from 3 to 10 ft (1–3 m) in height. Their origin and function remain mysteries. From the mid-1960s through the early 70s, the Plain of Jars was the scene of heavy fighting between the Pathet Lao and U.S.-backed troops.